ln.templates/ln.templates/TemplateReader.cs

// /**
//  * File: TemplateReader.cs
//  * Author: haraldwolff
//  *
//  * This file and it's content is copyrighted by the Author and / or copyright holder.
//  * Any use wihtout proper permission is illegal and may lead to legal actions.
//  *
//  *
//  **/
using System;
using System.IO;
using System.Net;
using ln.templates.html;

namespace ln.templates
{
    public class TemplateReader : ElementReader
    {

        public virtual TemplateDocument TemplateDocument => Document as TemplateDocument;

        protected TemplateReader()
        {
        }

        public override DocumentElement CreateDocument() => new TemplateDocument();
        public override Element CreateElement(string tagName) => TemplateElement.Create(tagName);

        public override void CloseTag(string tagName)
        {
            Element saveCurrentElement = CurrentElement;
            base.CloseTag(tagName);
            
            if (saveCurrentElement.HasAttribute("v-slot") && (saveCurrentElement.Parent is TemplateElement parentElement))
            {
                parentElement.SetSlot(saveCurrentElement.GetAttribute("v-slot"), saveCurrentElement);
                parentElement.RemoveChild(saveCurrentElement);
                saveCurrentElement.RemoveAttribute("v-slot");
            }
        }

        public override void Text(string text)
        {
            if (text.Contains("{{"))
            {
                int pOpen = 0;
                int pClose = 0;

                while (pOpen < text.Length)
                {
                    pOpen = text.IndexOf("{{", pClose);
                    if (pOpen == -1)
                        pOpen = text.Length;

                    string preText = text.Substring(pClose, pOpen - pClose);
                    if (preText.Length > 0)
                    {
                        CurrentElement.AppendChild(CreateTextElement(preText));
                    }

                    if (pOpen == text.Length)
                        break;

                    pOpen += 2;

                    pClose = text.IndexOf("}}", pOpen);
                    if (pClose == -1)
                        throw new FormatException("missing }}");

                    string expr = text.Substring(pOpen, pClose - pOpen);

                    pClose += 2;

                    CurrentElement.AppendChild(new ExpressionElement(expr));
                }

            } else
            {
                CurrentElement.AppendChild(
                    CreateTextElement(text)
                );
            }
        }


        public static TemplateDocument Parse(string source)
        {
            using (StringReader reader = new StringReader(source))
                return ReadTemplate(reader);
        }
        public static TemplateDocument ReadTemplate(string filename)
        {
            using (StreamReader reader = new StreamReader(filename))
                return ReadTemplate(reader);
        }
        public static TemplateDocument ReadTemplate(TextReader reader)
        {
            var templateReader = new TemplateReader();
            templateReader.Read(reader);
            return templateReader.TemplateDocument;
        }

    }
}